In general in an internal combustion engine, fuel is supplied from the tank to the supply line of a downstream high-pressure pump by means of a fuel pump. The high-pressure pump supplies the fuel into a reservoir or a fuel rail. This fuel supply unit may preferably be controllable in such a way that only the amount of fuel that is actually required is supplied and there is no unnecessary pump output. In internal combustion engines with high-pressure direct injection, a high-pressure fuel pump must supply fuel to the reservoir or the fuel rail. The fuel supply device, consisting of a low-pressure pump and the high-pressure pump, is designed to supply only the amount of fuel that is actually required according to the injection quantity and the fuel pressure level.
The fuel mass can be influenced by design-specific actuators that are subject to a time lag. In engines with stroke change-over, a very rapid change in the air mass in the cylinder is caused by the change-over of the valve stroke characteristic curve. Due to this altered air mass, the injection mass must also be altered accordingly, which in turn requires a very rapid adjustment of the actuation of the delivery rate of the fuel pump.
In the prior art, fuel was previously firstly injected in motor vehicles by means of an injector. For this, a suitable quantity of fuel for the next stroke is supplied by a pump when the system is to change to the next stroke for example. However, this does not take into consideration that, for example, the pump provides the quantity of fuel with a certain delay so that the quantity of fuel may in some circumstances be pumped into an associated fuel rail too early or too late. Furthermore, too much or too little fuel may as a result thus be injected by the injectors for example, resulting in a subsequent adjustment of the supposedly insufficient quantity of fuel, even though the correct quantity of fuel had been determined beforehand, but was provided too early or too late.